Flame-retardant polyesters and thermosetting compositions based thereon

ABSTRACT

This invention relates to brominated polyesters, based on diols and as co-reactants a brominated maleic acid, a brominated tetrahydrophthalic acid, anhydrides or brominated monomeric esters of the anhydrides thereof, which are substantially free of dibromosuccinate and dibromohexahydrophthalate groups, contain bromine end groups and possess excellent flame-retardant properties, excellent thermal stability, excellent resistivity to ultraviolet light and can be used as flame-retardant plasticizers and when containing unsaturated groups, derived from nonhalogenated unsaturated polycarboxylic acids, can be used in molding applications to form aesthetically attractive thermoset articles characterized by excellent chemical, physical and electrical properties.

A United States Patent Smith et al.

[451 Oct. 10, 1972 [54] FLAME-RETARDANT POLYESTERS AND THERMOSETTING COMPOSITIONS BASED THEREON [72] Inventors: Percy L. Smith, Dunbar; Lowell R.

Comstock, South Charleston, both of W. Va.

[73] Assignee: Union Carbide Corporation, New

York, N.Y.

[22] Filed: Nov. 23, 1970 [2]] Appl. No.: 92,238

Related US. Application Data [63] Continuation-impart of Ser. No. 715,977,

March 26, 1968, abandoned.

[52] US. Cl. ..260/869, 260/40 R, 260/75 H,

' 260/865 [51] Int. Cl. ..C08f 21/00, C08f 21/02 [58] Field of Search ..260/75 H, 869

[56] References Cited FORElGN PATENTS OR APPLICATIONS France Canada Primary Examiner-Melvin Goldstein Attorney-Paul A. Rose, A. J. Cozzi and James C. Ar-

vantes [57] ABSTRACT flame-retardant plasticizers and when containing unsaturated groups, derived from non-halogenated unsaturated polycarboxylic acids, can be used in molding applications to form aesthetically attractive thermoset articles characterized by excellent chemical, physical and electrical properties.

19 No Drawings FLAME-RETARDANT POLYESTERS AND THERMOSETTING COMPOSITIONS BASED THEREON This application is a continuation-in-part application of our copending application, Ser. No. 715,977, filed Mar. 26, 1968, now abandoned.

This invention relates to. flame-retardant polyesters, a process for the preparation thereof and to thermosetting compositions based thereon. More particularly, this invention relates to brominated polyesters based on diols and as co-reactants, a brominated maleic acid, a brominated tetrahydrophthalic acid, anhydrides or brominated monomeric esters of the anhydrides thereof, which are substantially free of 15 dibromosuccinate groups and dibromohexahydrophthalate groups, contain bromine end groups and possess excellent flame-retardant properties, excellent thermal stability, excellent resistivity to ultraviolet light and can be used as flame-retardant plasticizers for urethane or vinyl resins and when containing unsaturated groups, derived from non-halogenated unsaturated polycarboxylic acids, can be used in molding applications to form aesthetically attractive thermoset articles, characterized by excellent physical, chemical and electrical properties which are useful as structural elements such as fenders, dashboards and other like component parts of automobiles.

The brominated polyesters of this invention have: an acid number of less than about 100, generally about 10 to about 60 and preferably about 25 to about 50; contain at least about 2 percent by weight combined bromine, generally about 2 to about 40 percent by weight combined bromine and preferably about 10 to about 25 percent by weight combined bromine based on the weight of the polyester; have bromine end groups; are the condensation reaction products of a diol and as co-reactants, a brominated maleic acid, a brominated tetrahydrophthalic acid, anhydrides or brominated monomeric esters of the anhydrides thereof; and are substantially free of dibromosuccinate groups and dibromohexahydrophthalate groups.

It is to be understood that mixtures of reactants noted in this application can be used if so desired.

Illustrative of suitable diols for purposes of this invention are those having the formula:

Formula I Rt .L L ,1. HO \CHz/m i2 \CH jg H wherein the sum of m p is at least 1, generally 1 to 20 inclusive, preferably 4 to inclusive and R and R which can be the same or different, are hydrogen or alkyl and when alkyl, containing one to carbon atoms inclusive, preferably one to 10 carbon atoms inclusive. Specific compounds include, among others, ethylene glycol, propylene glycol, butanediol-l,2, butanedioll ,3 butanedioll ,4, hexanediol-l ,6, decanediol-l ,10, neopentyl glycol and the like.

Also suitable are the ether diols having the formula:

FORMULA u wherein a has a value of at least 1, preferably 2 to 6 inclusive, and 2 has a value of at least 2, preferably 2 to 10 inclusive. Among compounds falling within the scope of this formula are diethylene glycol, dipropylene gllycol, triethylene glycol, tetraethylene glycol, and the Also suitable are the polyalkylene glycols such as polyethylene glycol and polypropylene glycol, having molecular weights ranging from about 1,100 to about 20,000.

In one aspect of this invention by which the brominated polyesters are prepared, a diol is condensed with any one or a mixture of compounds of F orpoint 166-167 C. re ortcd b Alex M K 101, 1196 [1925]) p y c enzle JCS Formula IV.Iso-dibromosuccinic acid anhydride Formula V.A dibromohexahydro-phthalic acid Br ii-OH wherein z=0 or 1 Formula VI.A dibromohexahydro-phthalic acid anhydride H3)x E WhFtElILEE?!) 9 1. V...

isom erization to the fumarate groups. Tetrahydrophthalic acids or anhydrides thereof can alsobe brominated at room temperature, about 25 C., using a reaction solvent such as benzene.

The condensation reaction between the diols and the brominated compounds of Formulas Ill-VI to produce the .polyesters of this invention is carried out at elevated temperatures on the order of about l65 C. to about 225 C; and preferably about 170 C. to about 200 C. for a period of time sufficient to produce a polyester having an acid number of less than about 100, being substantially free of dibromosuccinate groups and dibromohexahydrophthalate groups and having bromine end groups.

In conducting the reaction between the brominated compounds of Formulas lll-Vl and the desired diol, the diol is used in at least stoichiometric amounts, generally at least about one present in excess of the stoichiometric amount and preferably about one percent to about percent in excess of the stoichiometric amount.

For purposes of stoichiometric calculations, amounts of diol are based on the total amount of acidic reactants in the reaction mixture. The acidic reactants include the brominated acids and anhydrides thereof as previouslydefined as well as monomeric esters of the brominated acid anhydrides as will be defined subsequently. Acidic reactants also include other acids and anhydrides thereof which can be used, if desired, in producing the polyesters of this invention. Acidic reactants also include hydrogen bromide which is split off during the condensation reaction. For purposes of stoichiometric calculations, one mole of hydrogen bromide is deemed to split off per mole of brominated 3 compound of Formulas Ill-VI used.

Illustrative of suitable unsaturated polycarboxylic acids which can be used with the brominated materials to produce the polyesters of this invention are those having the formula:

FORMULA Vll tetrahydrophthalic acid, 3-carboxy cinamic acid and,

the like.

If desired, the acid anhydrides of the acids previously described in the two preceding paragraphs can be used per se orv in admixture with the acids.

Also, if desired, aromatic polycarboxylic acids, saturated polycarboxylic acids, anhydrides tHereof or monocarboxylic acids can be used, in conjunction with the unsaturated polycarboxylic acids or the anhydrides thereof and the brominated materials, to produce the polyesters of this invention.

Illustrative of saturated polycarboxylic or aromatic polycarboxylic acids include, among others, phthalic acid, hexahydrophthalic acid, tetrachlorophthalic acid, succinic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, and the like.

The presence of maleic acid, tetrahydrophthalic acid and anhydrides thereof in the reaction mixture can be effected by formulating a mixture containing the above-noted materials and brominating only a portion thereof.

For purposes of illustration, the reactions involving bromination and condensation to the polyesters of this invention can ideally be represented as shown below. The reactants, for purposes of simplicity and clarity, are shown as maleic acid anhydride and a glycol HO- A-Ol-l, wherein A is the nucleus of the glycol.

Reaction No. 1.Bromination Polyester containing monobromomaleate groups and/or monobromofumaratc groups HBr Polyester bromine terminated and tree of dibromosuccinate groups Br- H-C Brill Reaction No. 5.Reaction between free glycol and 0 unreacted HBr C. HBr HOA-0H Br--AOH HOH (bromohydrln removed as overhead) For purposes of illustration, the reactionsinvolving a. tctrahydrophthalic acid and a diol can be Illustrated by Reactions 1A-5A.

Reaction No. 4.Reaction between polyester and Reaction No. 1A.-Bromination Blg COOH Br COOH C O OH Br O OH Bromine Tetrahydro- Dibromohexahydrophthalic acid phthallc acid Reaction No. 2A.Condensation reaction Polyester containing monobromotetrahydrophthalate groups ill monomeric esters is below about 150 C., generally Reaction No. 4A.Reaction between polyester and about 50 C. to about 120 C., and preferably about 50 C. to about 75 C.

The resultant monomeric esters are then brominated in a manner previously described, with respect to the monomeric esters based on a tetrahydrophthalic acid anhydride. The bromination of monomeric esters based on maleic acid anhydride is conducted at temperatures below about C. in order to insure prevention of isomerization to the fumarate groups.

The production of a monomeric ester and the bromination thereof can be illustrated by Reactions 7 below:

Reaction No. 6.-Production of the monomeric ester Malelc acid 0 lycol I anhydride Monomeric ester Reaction No. 7.Bromination of the monomeric ester Polyester, bromine terminated 40 and free of dibromohexa- H hydwphthalate groups CHCOA-OH 25o. BrCH-C-O-AOH on Neale-finesesiieaseqe lIQ- CHrCrOH The reactions involving other reactants'of Formulas Analysis of the polyesters of this invention to deter:

Ill-VI and diols can be represented ideally in a manner as shown by Reactions l-5.

These reactions are believed to be the primary reactions, in idealized form, although not the entire reactions involving the brominated materials and the diols to produce the polyesters of this invention.

In another aspect of the present invention, rather than brominating the maleic acid anhydride or the tetrahydrophthalic acid anhydride, these compounds can first be reacted with the desired diol to form the monomeric ester, the monomeric ester brominated to the dibromo monomeric ester and thereafter condensed in the presence of an additional amount of a diol in amounts previously described to produce the polyesters of this invention. The preparation of polyesters by this method is illustrated by Example 3 of this application.

In carrying out this reaction, it is preferred that a diol be present in an amount of at least about one mole diol per mole of total anhydride content to produce the corresponding ester.

. The temperature at which these anhydrides are reacted with the diols to form the corresponding 65 als:

products useful in the automotive industry, boat industry and the like.

In formulating such compositions which are to be used in molding applications, it is customary to admix, with the unsaturated polyesters, the following materil. A polymerizable ethylenically unsaturated monomer which serves to cross-link the unsaturated polyester to a thermoset product.

- ides 2. A peroxide which serves to accelerate the crosslinking reaction.

3. Fillers,-including fillers which serve as reinforcing agents.

Illustrative of suitable polymerizable, ethylenically unsaturated monomers are the vinyl monomers having the formula:

Formula. VIII B. CH1: (ll-R whe'reinR'is hydrogen, halogen or alkyl, i.e., methyl, R is a group having an unsaturated .carbon-to-carbon, carbon'-to-oxygen, or carbon-to-nitrogen group in conjugation with the vinyl group. Groups having such unsaturation in conjugation with the vinyl group are aryl, ketonic, heterocyclic, nitrile, carbalkoxy, carboxy and amido.

Specific vinyl monomers include the following:

Wherein R is aryl; styrene, halogenated styrenes such as chlorostyrene, A-chlorostyrene, p-iodostyrene, mflurostyrene, dichlorostyrene and the like; alkyl substituted styrenes such as p-methylstyrene, A-methylstyrene, p-ethylstyrene, o-tert-butylstyrene and the like; alkoxy and aryloxy substituted styrenes such as pethoxystyrene, p-propoxystyrene, p-phenoxystyrene and the like;

Wherein R is ketonic; ethyl vinyl ketone, n-propyl vinyl ketone, phenyl vinyl ketone and the like;

Wherein R is heterocyclic; vinyl pyridine, vinyl quin oline, vinyl pyrrole, vinyl carbazole, vinyl thiophene and the like;

Wherein R is nitrile; acrylonitrile and the like;

Wherein R is amido; acrylamide, bicycloheptylacrylamide, diacetoneacrylamide and the like;

Wherein R is carboxy; acrylic acid and the like;

Wherein R is carbalkoxy; methyl acrylate, methyl methacrylate, butyl acrylate, octyl acrylate, lauryl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate and the like.

Also suitable is diallylphthalate and the like.

The amount of ethylenically unsaturated monomer used can vary over wide limits. For example, the monomer can be used in amounts of about 10. to about 60 percent by weight based on the combined weight of the monomer and the polyester... It is preferred to use about 20 to about 50 percent by weight ethylenically unsaturated monomer, based on the combined weight of the monomer and polyester.

Among suitable peroxides that can be used are those which function as free-radical polymerization initiators. Examples of such peroxides are the hydroperoxsuch as tert-butyl hydroperoxide, cumene hydroperoxide, para-menthane hydroperoxide and the like; peroxy esters such as di-tert-butyl diperoxyphthalate, tert-butylperoxyacetate and the like; alkyl peroxides such as di-tert-butyl peroxide, dibenzyl peroxide and the like; ketone peroxides such as methyl ethyl ketone. peroxide, cyclohexanone peroxide and the like; acyl peroxides such as benzoyl peroxide, parachlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide,

lauroyl peroxide and the like.

The amount of peroxide used is sufficient to effect a cross-linking or thermosetting of the composition in a relatively short period of time. As a rule the amount used is about 0.1 to about 5 percent and preferably about 0.5 to about 2 percent by weight based on the weight of the polyester.

Fillers which are commonly employed in polyester compositions include, among others, glass fibers, clay, calcium carbonate, silica, hydrated alumina, antimony oxide, and the like. These materials are generally used in amounts of about 2 to about percent by weight I based on the weight of the polyester resin.

In addition, if desired, phosphorus containing compounds such as tri(2-chloroethy1)phosphate can be added to the compositions of this invention. I

The compositions of this invention can be prepared by mixing the components in a suitable apparatus such as a Cowles dissolver, at temperatures on the order of about 25C. to about 50 C.

Once formulated, the compositions can be formed into thermoset articles of desired shape, particularly thermoset articles such as automobile fenders, dash: boards, building panels, boats and the like. The actual forming cycle used such as hand lay-up, spray-up and molding using matched metal molds, will varyand depend upon the composition being used and the ultimate article formed.

Suitable molding cycles are conducted at temperatures on the order of 25 F. to about 250 F. for periods of time ranging from about 0.5 minute to about 5 minutes.

The following examples further illustrate the present invention.

EXAMPLE 1 This example illustrates the preparation of a polyester based on a pre-brominated maleic acid anhydride.

(a) bromination of maleic acid anhydride Into preparation reaction flask equipped with a mechanical stirrer, thermometer, condenser, dropping funnel, and gas-inlet tube, there was charged five (5) moles of maleic acid anhydride. The maleic acid anhydride was heated to a temperature of about C. and 1.21 moles bromine were added dropwise into the flask while thecontents of the flask were constantly stirred and maintained under a nitrogen gas atmosphere. After the addition of the bromine, the contents of the flask were heated for 1 hour at a temperature of about 150 C. At the end of the 1 hour period, the temperature of the reacted mixture dropped to about 50 C. and the bromine color (dark red) disappeared therefrom indicating completion of the bromination reaction.

(b) preperation of the brominated polyester Into the flask containingthe brominated maleic acid anhydride, (a) above, there was added one (1) mole of phthalic acid anhydride and 6.85 moles of ethylene glycol. The resultant mixture was heated to a temperature of C. and maintained at this temperature for 5.5 hours. The resultant polyester had an acid number of 60 and was characterized by bromine end groups and by substantially complete absence of dibromosuccinate groups as determined by Nuclear Magnetic Resonance.

The polyester was cooled to a temperature of about 150 C. and hydroquinone, a stabilizer, was added thereto in an amount of 0.01 percent by weight, based on the weight of the polyester. Styrene was then admixed with the polyester to obtain a styrene solution containing 30 percent by weight styrene.

EXAMPLE 2 This example illustrates the preparation of a polyester based on a pre-brominated maleic acid anhydride, brominated in a reaction mixture containing in addition to the maleic acid anhydride, an aromatic acid anhydride and die] reactants.

Into a reaction flask equipped with a mechanical stirrer, thermometer, condenser, dropping funnel, and gas-inlet tube, there was charged five (5) moles of maleic acid anhydride, one (1) mole of phthalic acid anhydride and 6.85 moles of ethylene glycol. Bromine, in an amount of 1.21 moles, was added dropwise into the reaction flask while the contents of the reaction flask were constantly stirred and maintained under a nitrogen gas atmosphere. The rate at which the bromine was added was such that the contents of the reaction flask were maintained at a temperature of about C. After the bromine addition and completion of the bromine reaction, evidenced by disappearance of the bromine color, the reaction mixture was heated to a temperature of 175 C. and maintained at this temperature for 5.5 hours. The resultant polyester had an acid number of 60 and was characterized by bromine end groups and by substantially complete absence of dibromosuccinate groups.

The polyester was cooled to a temperature of about 150 C. and hydroquinone added thereto in an amount of 0.01 percent by weight, based on the weight of the polyester. Styrene was then admixed with the polyester to obtain a styrene solutioncontaining 3.0 percent by weight styrene.

In order to demonstrate the excellent properties of the polyesters of this invention, various properties were determined with respect to the polyesters of Example 1 and Example 2 and compared to the properties of a polyester, referred to as Control 1 prepared by a process in which the polyester was prepared first and then brominated. Control 1 was prepared as follows:

Into a reaction flask equipped with a mechanical stirrer, thermometer, condenser, dropping funnel and gas-inlet tube, there was charged five (5) moles of maleic acid anhydride, one (1) mole of phthalic acid anhydride and 6.3 moles of ethylene glycol. The mixture was heated for 5.5 hours at a temperature of 200 C. The resultant polyester had an acid number of 18.8. The resultant polyester was cooled to a temperature of about 150 C. and maintained at about 150 C. while bromine, in an amount of 1.21 moles, was added dropwise in the flask while the contents of the flask were constantly stirred and maintained under a nitrogen gas atmosphere. After the addition of the bromine, the contents of the flask were heated for 1 hour at a temperature of about 150 C. At the end of the one hour period, the temperature of the reaction mixture dropped to about 50 C. and the bromine color disappeared therefrom indicating completion of the bromination reaction. To the post brominated polyester, which had an acid number of 53 and was characterized by the substantial presence of dibromosuccinate groups as determined by Nuclear Magnetic Resonance, there was then added 0.01 percent by weight hydroquinone, based on the weight of the polyester. Styrene was then admixed with the polyester to obtain a styrene solution containing percent by weight styrene.

The amount of reactants and time of reaction in each case, i.e., Example 1, Example 2 and Control 1, are as tabulated below.

Properties determined with respect to polyesters of Example 1, Example 2 and Control 1 are set forth in Table 1.

TABLE 1 Con- Con- Properties trol trol Ex. Ex. Ex. Ex. of Polyester 1 2" 1 1* 2 2* Percent by weight combined bromine 17.1 17.1 15.3 15.3 15.3 15.3 Acid number 18.8 18.8 60 60 60 60 Acid number after post bromination of polyester 53.0 53.0

Properties of Styrene- Polyester Composition Percent by weight combined bromine 12 12 10.6 10.6 10.6 10.6 Acid number 35.8 35.8 35.0 35.0 38 38 Viscosity, centipoises 1528 1000 1000 900 900 Gel time, minJsec. 3/2 1/47 2/58 Exothen'n temp., C. 191 21 1 200 Peak time, min/sec. 5/5 2/50 4/47 Color, Gardner Scale 3 3 3 3 3 3 Properties of Cured Styrene-Polyester Composition Color, Gardner Scale 7 7 4 4 4 4 Heat distortion temp.,

C. 69 65 131 120 115 Tensile strength, psi. 8000 8000 7500 7500 8315 8000 Elongation, percent 1.5 1.5 1.5 1.5 1.5 1.5

Flame-retardant properties, HLT-l5 Ultraviolet light stability, A R

Heat stability, weight loss after heating at 225C. for 24 hours, percent Excellent throughout this application were made at 25 C. using a Brookfield viscometer which was operated at 30 rpm with a No. 3 spindle.

Compositions noted as being cured in Table I and throughout this application were cured or thermoset by adding thereto 1.0 percent by weight benzoyl peroxide, based on the total weight of the composition and subjecting the resultant compositions to the following heating cycle:

2 hours at a temperature of 60 C.

3 hours at a temperature of 125 C.

Tensile strength determinations noted in Table I and throughout this application were carried out according to the procedure described in ASTM test 63 8-64T.

Elongation determinations noted in Table I and throughout this application were carried out according to the procedure described in ASTM test 63 8-64T.

Gel time determinations, including gel time, exotherm temperature and peak time, notedin Table I and throughout this application were carried out according to the standard tests of the Society Plastics Industry. I-ILT 15 Test described in Hooker Electrochemical C0. brochure MLT-l 52-3, 9/20/55.

Light stability reported as. AR in Table l and throughout this application was determined according to thefollowing procedure:

Panels, 1 inch by 2 inches by of an inch, were molded from the compositions to be tested and cured in a manner previously described. These panels were then placed in a photovolt meter equipped with a monochromatic filter which allowed only light having a 440 millimicrons, .blue light, to strike the panels. The amount of blue light passing through each panel was measured by a photovolt meter, Model No. 610, sold by the Photovolt Corp. and recorded as the initial blue light reflectance of each panel. Thereafter, each panel was placed in anair circulating oven, 3 inches from a 275 watt sunlamp which was also positioned in the air circulating oven. Each panel was allowed to remain in the oven, which was at a temperature of 80 C., for 96 hours with the sunlamp on. The blue light reflectance was again determined for each panel.

The change in reflectance, reported as A R, and obtained by subtracting the initial blue light reflectance from the blue light reflectance after the heating step, is a measure of the-degradation of each composition. The greater the A R, the greater the degradation, that is, the poorer the ultraviolet light stability.

EXAMPLE 3 tents of the flask. After completion of the bromination reaction, evidenced by disappearance of the bromine color, three (3) moles of maleic acid anhydride were added to the contents of the flask. The temperature of the reaction mixture was raised to 180 C. and maintained at 180 C. for 5.5 hours. The resultant polyester had an acid number of 50 and was characterized by bromine end groups and by the substantially complete absence of dibromohexahydrophthalate groups.

The polyester was cooled to a temperature of about 150 C. and hydroquinone was added thereto in an amount of 0.01 percent by weight, based on the weight of the polyester. Styrene was then admixed with the polyester to obtain a styrene solution containing 30 percent by weight styrene. To this solution there was then added tri(2-chloroethyl)phosphate in an amount of 3 percent by weight, based onthe weight of the styrene solution.

The properties of the resultant composition were determined and-compared to the properties of a .composition which contained a post-brominated polyester Control 2. This polyester was prepared as follows:

Into a reaction flask equipped with a mechanical stirrer, thermometer, condenser, dropping funnel and gas-inlet tube, there was charged one (1) mole of tetrahydrophthalic acid anhydride, three (3) moles of maleic acid anhydride and 4.25 moles of ethylene glycol. This mixture was heated under a nitrogen gas atmosphere at a temperature of 200 C. to an acid number of 40. The resultant polyester was cooled to a temperature of about C. and bromine, in an amount of 0.95 mole, was added thereto dropwise, while the contents of the flask were constantly stirred and maintained under a nitrogen gas atmosphere to brominte the polyester in a manner previously described.

To the brominated polyester, there was then added 0.01 percent by weight hydroquinone and styrene to obtain a styrene solution containing 30 percent by weight styrene. Tri(2-ch1oroethyl)phosphate in an amount of 3 percent by weight was then added to the styreneepolyester solution.

Properties of each composition are noted in Table 11.

Based on the weight of the polyesters, the percent by weight combined bromine of Control 2 was 19 and that of Example 3 was 17.4

A number of polyesters were prepared, compositions formulated therefrom and tested. The. formulation of the compositions tested and the results of the test are set forth in Table 111.

The polyesters noted in Table III were prepared as follows:

Example 4 polyester was prepared according to percent by weigh I the procedure described in Example 3, using the fol- S combined bronine l2 l2 l2 tyrene, percent y kwmg reactants' weight 30 30 30 30 30 Hydroquinone, percent Reactams Moles by weight 0.005 0.005 0.005 0.005 0.02 Methyl tetrahydrophthalic Kimzchlomethyl) acid anhydride 1.0 g fjgr gi g 3 3 3 3 gig' if jg igi' 3 Acid number 29 so 30 29 Bromine 0.95

I Gel time,min./sec. 2/43 3/10 3/40 Control 3 polyester was prepared according to the s t g um. 3 L 54 procedure described for Control 2, using the following zi f'ggg' g' zgi I 3 3 g reactants:

Properties of Cured Reactants Moles 1 5 Styrene-Polyester Methyl tetrahydrophthalic Composition acid anhydride 1.0 Maleic acid anhydride 3.5 Ethylene glycol v 4.95 Color, Gardner Scale 8 7 7 4 2 Bromine 0.95 Heat distortion temp.,

C. 65 106 65 126 124 Tensile stren th, si 6100 7550 6350 8000 Example 5 Polyester was P p accol'dlng 20 Elongatiomp erce l'n 1.3 1.9 1.5 1.1 1.5

theprocedure described in Example 2, using the folant properties, l-lLT-15 Excel1entlowmg reactants' Flammability ASTMD- 635-561 Sel f- I Reactants Moles B Maleic acid anhydride 3.0 25 A number of polyesters were prepared based on Tefahydmifhthahc brominated maleic acid anhydride using the reactants acid anhydnde 1.0 Ethylene glycol, 4.5 set forth in Table IV and conducting the reactions rela- Bmmme tive thereto in a manner described in Example 1.

Properties of the polyester, properties of the com- Comrol polyester was Prepared a manner positions based thereon and formulation of the comdescribed for Control 1, using the following reactants: positions are also Set f th i bl 1 Also, these polyesters were characterized by f iq q h d fg bromine end groups and by the substantially complete 381C 3C1 an ['1 (3 I r r Tetrahydro hthzlic 3 absence of dibromosuccmate groups. acid anhydride 1.0 5 V i Ethylene glycol 4.4 TABLE IV Bromine 0.95

Polyester Control 5 polyester was prepared in a manner Ream 7 8 described for Example 2, with the exception that fu- 40 maric acid was used in lieu of the maleic acid an- Malmficid h dride anhydride, moles 3.0 2.0 1.0 3.0 2.0

y Tetrahydrophthalic acid Reacmms Moles griillttrygligigzgirgoles 1.0 1.0 1.0 1.0 1.0 Fumaric acid 5.0 Phthalic acid anhydride 1.0 gg i g fgf 5 9 glym moi... gy 4.5 3.4 2.2 5.5 4.4

"" Bromine, moles 0.95 0.75 0.49 0.95 0.95

Polyesters of Examples 4-5 were characterized by Pmpemes of bromine end groups and by the substantially complete Polyester absence of dibromosuccinate and/or dibromohexahydrophthalate groups, as determined by Nuclear percemby weight Magnetic Resonance. combined bromine 17.5 17.1 17.1 14.5 17.1

Polyesters of Controls 3-5 were characterized by the presence of substantial amounts of dibromosuccinate Properties&

Formulation of and/or dibromohexahydrophthalate groups, as deterstyrewpolyester mined by Nuclear Magnetic Resonance. Composition TABLE III Percent by wetght Properties Com Com Com Ex Ex combined bromine 12.3 12.0 12.0 10.0 12.0

i Styrene, percent of Polyester "0 3 "0| 4 "0] 5 I 4 5 y ight 30 30 30 30 30 Hydroquinone, Percent by weigh! percent by weight 0.02 0.02 0.02 0.02 0.02

combined bromine 19 19 17.1 17.1 17.1 gsf gglg P l' l gii ntlif f pGerlctent by weight 3.0 3.0 3.0 3.0 3.0

e ime, r n gzriiigir min./sec. 3/30 3/49 3/51 3/53 3 53 Exotherm temp.,C. 225 224 208 214 197 Properties of Cured Styrene- Polyester Composition Color, Gardner Scale 2 3 2 3 2 Heat distortion temp., C. Tensile strength, psi

Elongation, percent Flexural strength ASTMD-790-66 Flexural modulus ASTMD-79066 Flame-retardant properties,

l-lLT-l5 Excellent Ultraviolet light H stability, A R 45 49 50 53 47 The unique properties of the polyesters of this inventionare further evidenced by a comparison of the properties thereof with the properties of prior art polyesters. The polyesters, composition formulated therefrom and properties thereof are set forth in Table V.

EXAMPLE 11 Polyester was prepared in a manner described in Example 1 using the following reactants:

Reaetants Moles Maleic acid anhydride 5.0 Phthalic acid anhydride 1.0 Ethylene glycol 6.85 Bromine 1.38

This polyester contained 17.1 percent by weight combined bromine.

Control 6 polyester was prepared in a manner described in Example 1 usingthe following reactants:

Reactants Moles Maleic acid anhydride 5.0 Phthalic acid anhydride 1.0 Ethylene glycol 6.85 Chlorine 1.38

Control 7 polyester was prepared according to Example 1 of the Ogura et a1. patent, Pat. application Ser. No. 10,546 of 1960, using the following reactants:

'1ri( 2 -chlorocthyl )phosphate,

percent by weight Acid number 118 50 50 Viscosity, centipoises 2000 Color, Gardner Scale 8 4 3 Properties of Cured Styrene- Polyester Composition Color, Gardner Scale 1 1 6 4 Heat distortion temp., C 1 13 65 122 Tensile strength, psi 4500 6000 8000 Elongation, per cent 1 1.4 '1.7 Flexural strength, psi 13,000 13,000 17,000 F lame-retardant properties, BLT-15 Poor Poor excellent Ultraviolet light 1 stability, A R 62 68 47 The unique properties of the polyesters of this invention, that is, the fact that these polyesters are both flame-retardant and characterized by improved properties as described, was further evidenced on using monobromomaleic acid to produce a polyester according to the procedures described in Example 1. The polyester produced from monobromomaleic acid had exceedingly poor flame-retardant properties and could not be classified as a commercially acceptable flameretardant polyester.

Polyesters prepared using the following polyols had properties comparable to the properties of the polyester of Example 1.

Diethylene glycol Propanediol-l ,2

Butanediol-l ,4

Poly(ethylene glycol) What is claimed is:

1. Process of preparing a brominated polyester which comprises condensing, at a temperature of about C to about 225 C, a reaction mixture containing at least a stoichiometric amount of a diol selected from the group consisting of a diol having the formula:

R r 1. ,1. HOTCHz/m i2 \CH jp OH wherein the sum of m p is 1 to 20 inclusive and R and wherein, a has avalue of 2 to 6 inclusive and 2 has a value of 2 to 10 inclusive, a diol which is a polyalkylene glycol having a molecular weight of about 1,100 to about 20,000; and mixtures thereof; and an acidic reactant selected from the group consisting of isodibromosuccinic acid, a dibromohexahydrophthalic acid having the formula:

Br COOH B! COOH wherein x is or 1; anhydrides thereof, the dibrominated monomeric ester of maleic acid anhydride and a diol as defined; the dibrominated ester of a tetrahydrophthalic acid anhydride and a diol as defined; and mixtures thereof in amounts sufficient to yield a polyester containing at least about 2 percent by weight combined bromine, for a period of time sufficient to produce a polyester having an acid number of less than about 100, having bromine end groups and being substantially free of dibromosuccinate and dibromohexahydrophthalate groups.

2. Process as defined in claim 1 wherein the diol has the formula:

wherein the sum of m p is 4 to inclusive and R and R are hydrogen or alkyl containing 1 to 10 carbon atoms inclusive.

3. Process as defined in claim 1 wherein ethylene glycol is present as a diol reactant in producing the polyester.

4. Process as defined in claim 1 wherein phthalic acid or anhydride thereof is present in the reaction mixture.

5. Process as defined in claim 1 wherein maleic acid or anhydride thereof is present in the reaction mixture.

6. A brominated polyester having an acid number less than about 100, having bromine end groups, containing at least about 2 percent by weight combined bromine, and being substantially free of dibromosuccinate and dibromohexahydrophthalate groups, said polyester being the condensation reaction product of a mixture as defined in claim 1.

7. A brominated polyester as defined in claim 6 containing about 2 to about 40 percent by weight combined bromine.

8. A brominated polyester as defined in claim 6 which is the condensation reaction product of a mixture containing at least a stoichiometric amount of a diol and isodibromosuccinic acid or anhydride thereof.

9. A brominated polyester as defined in claim 6 which is the condensation reaction product of a mixture containing at least a stoichiometric amount of a diol and a dibromohexahydrophthalic acid or anhydride thereof having the formula:

Br coon Br 0 0 OH wherein at 0 or 1.

10. A brominated polyester as defined in claim 6 wherein the mixture contains at least a stoichiometric amount of a diol and a dibrominated monomeric ester of maleic acid anhydride and a diol.

11. A brominated polyester as defined in claim 6 wherein the mixture contains at least a stoichiometric amount of a diol and a dibrominated monomeric ester of a tetrahydrophthalic acid anhydride and a diol.

12. A brominated polyester as defined in claim 6 wherein the diol is present in the reaction mixture in an amount of about 1 percent to about 10 percent in excess of the stoichiometric amount.

13. A brominated polyester as defined in claim 6 wherein the diol has the formula:

wherein the sum of m p is 4 to 10 inclusive and R and R are hydrogen or alkyl containing 1 to 10 carbon atoms inclusive.

14. A brominated polyester as defined in claim 6 wherein ethylene glycol is present as a diol.

15. A brominated polyester as defined in claim 6 wherein there is present in the reaction mixture phthalic acid or anhydride thereof.

16. A brominated polyester as defined in claim 6 wherein there is present in the reaction mixture maleic acid or anhydride thereof.

17. A thermosetting composition comprising the polyester as defined in claim 16 and an ethylenically unsaturated monomer in an amount of about 10 to about percent by weight.

18. A thermosetting composition as defined in claim 17 wherein the ethylenically unsaturated monomer is styrene.

19. A thermosetting composition as defined in claim 17 containing a peroxide. 

2. Process as defined in claim 1 wherein the diol has the formula: wherein the sum of m + p is 4 to 10 inclusive and R1 and R2 are hydrogen or alkyl containing 1 to 10 carbon atoms inclusive.
 3. Process as defined in claim 1 wherein ethylene glycol is present as a diol reactant in producing the polyester.
 4. Process as defined in claim 1 wherein phthalic acid or anhydride thereof is present in the reaction mixture.
 5. Process as defined in claim 1 wherein maleic acid or anhydride thereof is present in the reaction mixture.
 6. A brominated polyester having an acid number less than about 100, having bromine end groups, containing at least about 2 percent by weight combined bromine, and being substantially free of dibromosuccinate and dibromohexahydrophthalate groups, said polyester being the condensation reaction product of a mixture as defined in claim
 1. 7. A brominated polyester as defined in claim 6 containing about 2 to about 40 percent by weight combined bromine.
 8. A brominated polyester as defined in claim 6 which is the condensation reaction product of a mixture containing at least a stoichiometric amount of a diol and isodibromosuccinic acid or anhydride thereof.
 9. A brominated polyester as defined in claim 6 which is the condensation reaction product of a mixture containing at least a stoichiometric amount of a diol and a dibRomohexahydrophthalic acid or anhydride thereof having the formula: wherein x 0 or
 1. 10. A brominated polyester as defined in claim 6 wherein the mixture contains at least a stoichiometric amount of a diol and a dibrominated monomeric ester of maleic acid anhydride and a diol.
 11. A brominated polyester as defined in claim 6 wherein the mixture contains at least a stoichiometric amount of a diol and a dibrominated monomeric ester of a tetrahydrophthalic acid anhydride and a diol.
 12. A brominated polyester as defined in claim 6 wherein the diol is present in the reaction mixture in an amount of about 1 percent to about 10 percent in excess of the stoichiometric amount.
 13. A brominated polyester as defined in claim 6 wherein the diol has the formula: wherein the sum of m + p is 4 to 10 inclusive and R1 and R2 are hydrogen or alkyl containing 1 to 10 carbon atoms inclusive.
 14. A brominated polyester as defined in claim 6 wherein ethylene glycol is present as a diol.
 15. A brominated polyester as defined in claim 6 wherein there is present in the reaction mixture phthalic acid or anhydride thereof.
 16. A brominated polyester as defined in claim 6 wherein there is present in the reaction mixture maleic acid or anhydride thereof.
 17. A thermosetting composition comprising the polyester as defined in claim 16 and an ethylenically unsaturated monomer in an amount of about 10 to about 60 percent by weight.
 18. A thermosetting composition as defined in claim 17 wherein the ethylenically unsaturated monomer is styrene.
 19. A thermosetting composition as defined in claim 17 containing a peroxide. 